Use of computational models to reconstruct and predict trichloroethylene exposure

Area of Science:

• Environmental Science
• Public Health
• Toxicology

Background:

• Groundwater and surface-water contamination occurred near the Gratuity Road site in Groton, Massachusetts.
• Primary contaminants identified include trichloro-ethylene (TCE), 1,1,1-trichloroethane (TCA), hexavalent chromium, chromium, and lead.
• Off-site residential groundwater wells were contaminated with TCE and TCA.

Purpose of the Study:

• To reconstruct and predict historical exposure to trichloro-ethylene (TCE) using computational models.
• To assess exposure risks to nearby populations from historical contamination not captured by remediation.
• To compare exposure to TCE via inhalation during showering versus ingestion of contaminated domestic water.

Main Methods:

• Utilized environmental transport models with numerical methods to approximate groundwater flow and contaminant transport.
• Developed a spatial and temporal database from transport models for exposure analysis.
• Employed a one-compartment model to compare TCE exposure from inhalation and ingestion routes.

Main Results:

• Groundwater concentrations of TCE frequently exceeded the EPA's Maximum Contaminant Level (MCL) of 5 ppb.
• Exposure to TCE via inhalation during showering was found to be nearly identical to exposure via ingestion of contaminated domestic water.
• Computational models demonstrated significant exposure risks to populations from historical contamination even after site remediation.

Conclusions:

• Remediation of hazardous waste sites does not eliminate historical contamination exposure risks for nearby populations.
• Inhalation of volatile organic compounds like TCE during showering is a significant exposure pathway, comparable to ingestion.
• Exposure analyses for volatile organic compounds must consider both inhalation and ingestion routes.